Elevator control system



1935. H. c. TURNBULL ELEVATOR CONTROL SYSTEM Filed Jan. '7, 1933 3 Sheets-Sheet l a com Al .0 M Al saw 0 com cow Al All cow 3m 3v 3? T All 8* 3w cow 8m A] com 03 cow 0 Alv Alv Q com 83 gm |v lv 8m 83 Sfi Q2 Iv 8* 8g 83 Q3 |v |v 3w 2E 33 m |v \W Y llv com 82 83 33 Iv iv 32 3Q 83 8g Iv K. x 1 25 83 23 m w 2260 IIY T E m. n5 Q .o. E6 62: 3523 Ev March 5, 1935.

H. c. TURNBULL 1,993,422

ELEVATOR CONTROL SYSTEM Filed Jan. '7, 1933 5 Sheets-Sheet 3 Patented Mar. 5, 1935 UNITED STATES PATENT OFFICE ELEVATOR CONTROL SYSTEM Harry 0. Turnbull, Toronto, Ontario, Canada Application January 7,

' 14 Claims.

The principal object of this invention is to devise a'system of operating variable voltage elevator controls which will ensure the accurate stopping of the car level with the landing under varying conditions of load and direction and speed of movement.

A further object is to provide a means for effecting the operation of such system which will be extremely reliable in operation and of simple and durable construction. 7

The principal feature of the invention consists in the novel method of regulating the values of the current produced by'the generator for supplying current to the motor for operating the car whereby the flow of current for demagnetizing the residual magnetism of the field windings of the generator is regulated by a resistance controlled by a weighing means which is responsive to the load on the car.

. In the accompanying drawings Figure 1 is a chart indicating in graphic form the varying stopping conditions with different loadings on the elevator car.

Figure 2 is an elevational view illustrating the assembly of the weighing and resistance control mechanism mounted on the elevator car.

Figure 3 is an enlarged sectional view of the dash-pot for checking the movement of the lever for supporting the car and operating the resist- 30, ance control device.

Figure 4 is an enlarged elevational view of the switching contact device for controlling the movement of the car.

Figure 5 is a diagram of the wiring of the application of the invention as herein shown and described.

The diagram shown in Figure 1 is based on an elevator having a capacity of 2000 pounds and over and a counterbalance of approximately 40%. The columns of numbers represent the load on the car in 200 pound variations and the net unbalanced loads considering the counterpoise. The arrows indicate the direction, up or down, of the pull of gravity due to unbalanced loads.

The distances from the plotted curves ,f, c, and g, e, to the centre line oo represent the relative power values that must be used to stop the car. With 800 pounds load on the car the elevator is evenly balanced so that the same power is required to stop the car when it is moving in either direction, the distance a o being equal to b-o. 1

With no load on car going up the power re- 50; quired for stopping the car is the same as that 1933, Serial No. 650,650

required for stopping with a load of 1600 pounds going down, the distance eo being equal to 11-0.

With no load on car going down the same power is required to stop the car as is required for 1600 pounds going up, the distance co being equal to h-0.

With 2000 pounds going up the minimum stopping power, represented by distance f-o is required, while with 2000 pounds going down the maximum power, represented by distance g-o is required.

The power required to stop the car is the product of a given counteracting force applied for a given period of time, and this product, as above illustrated varies widely for different loadings and directions of travel.

In the operation of variable voltage control elevators, the speed of the car is regulated by increasing or decreasing the voltage produced by the generator supplying the current to the motor. Control switches are used to reduce the speed of movement of the car to a very slow speed just before the car reaches a landing where a stop is to be made. When the car is at a predetermined distance from a landing, and the con trol switch on the car has been operated for making a stop, a selector stopping switch is antomatically operated to open the generator shunt field circuit to bring the car to a stop, but the exact distance the car will travel before stopping will vary, depending upon the load on the car, its direction of travel and the speed of the car when the stopping switch is operated and also upon the flux values of the generator which are afiected by the conditions of the load, direction and speed of the car and also the residual magnetism of the shunt field windings.

Various means for demagnetizing the generator fields have been proposed to control the stopping of the car but on account of the extremely variable factors a thoroughly dependable control has not to my knowledge been achieved.

The present invention provides a method of adjusting the demagnetizing current and the period of its application so as to ensure the car stopping exactly level with the floor under any condition of travel, from light to full load, either up or down travel, or when the car is operating on a short floor to floor run or a run of several floors. It will be appreciated that a high speed elevator having amaximum speed of from 500 to 600 feet per minute, on a short floor to floor run only approximately half speed can be attained before the car commences to slow down for the stop.

The flux values in the generator thus differ materially from those attained in a longer run and these vary in accordance with the length of the run.

In carrying this invention into effect as herein illustrated a lever 1, pivotally mounted on a bracket 2 secured to the lift beams 3 of the car, is attached to the lift cables 4 by the draw bolts 5. A compression spring 6 is arranged between the lever 1 and a plate 7 mounted on the lift beams and operates to sustain the weight of the car and its load. This spring may be adjusted to vary its pressure resistance and an adjusting screw '7 is shown mounted in the plate 7.

A dash pot 8 is pivotally mounted on the lever 1 and a piston 10 mountedbetween the stirrups 10' secured to the lift beams 3 operates in said dash pot against a fluid, "such as oil, contained therein, the piston having an adjustable opening 11 therethrough through which the oil is forced in either direction according to the movement of the car in response to loading conditions. When there is no load on the car the free end of :the lever 1 will assume its lowermost position and under full load it assumes its highest position; Any positions of the lever and between its extreme positions will, on account of the spring 6, be in direct ratio'to the load on the car.

A link 12 pivotally connected to the free end of the lever 1, is connected to the free end of a lever 13 secured to a shaft 14 journalled in a casing 15' mounted on the lift beams 3 of the car and the shaft is rotated by the up and down movement of the lever in its rotation on its pivot. 7

Within the casing 15 and mounted upon th shaft 14 isa spider 16 provided with four radiating arms. An electrically insulated plate 17 is mounted on each of the spider arms and upon each plate are mounted two pairs of brush holders 18. r P

Upon one of the end walls of the casing are mounted a plurality of concentrically arranged segmental contacts a, b, c, d, e, f, g, h, which are engaged by the brushes in the holders 18 which engage the rows of button contacts a b c d e fg h arranged concentric with the respective ring segments a, b, c, d, e, f, g, it. Each of the ring segments and button contacts is mounted on-an insulating base and is provided with a suitable wiring terminal at the opposite side of the base and binding posts 19 are arranged for grouping the wires from the button contacts. 7

As the load on the car varies, the action of the Weighing lever' 1 operates the spider 16 through the connections described so that the brushes engaging the ring segments travel over the button contacts, progressively making contact individually with same and completing electric circuits.

The wiring of the various circuits is illustrated in Figure 5.

In Figures 4 and 5 the contact groups co-operating with the several spider arms are marked, STU indicating slow speed timing up travel; STD indicating slow speed timing down travel; HTU indicating high speed timing for up travel; HTD indicating high speed timing down travel; SRU indicates slow speed resistance up travel; SRD indicates slow speed resistance down travel; HRU indicates high speed resistance up travel and HR!) indicates high speed resistance down travel.

' The wiring diagram illustrated in Figure 5 is merely elementary showing such connections as are necessary to illustrate the application of this invention and for convenience in illustration a car switch control lever is shown, though the system may be readily adapted to an automatic push button control or a combination of car switch and push button as may be desired.

As herein illustrated the car switch lever 20 is provided with a contact segment 21 which when the lever is moved to the right bridges contacts 22 and 23 thus completing an electric circuit through the up direction switch U as follows:--

From positive line wire +L at 28 to contact 22, through switch contact 21 to contact 23, to 29, through magnet coil of switch U to 30, to 31, to 32 on line wire L. The current passing through the coil of switch U picks up the solenoidwhich carries a plurality of contacts and closes contacts which complete the circuit for the generator shunt field as follows:-

From +L at 45 to contacts 35 and 36 to 46 through generator field winding GSF to 47 to contacts 38 and 37 to 48 and 49, through field resistance FR to 50 to 53 on L. This causes the generator to deliver current at low voltage to the elevator motor M. and the car starts upward at slowspeed. I When the car switch handle is moved further to the right and the segment 21 engages the contact 24 the. circuit is completed to the speeding switch H as follows:

A bridge is arranged on car switch 21 between the contact 24 on one side and a contact 27 on the opposite side and current from line wire +L flows from 28 to 22 through switch contact 21 to 24 through the bridge to 27 to contacts 54 and 55 of a speed control switch SC is closed, to 56 through magnet coil of switch H to 57 and to 32 on line wire L. It is the custom to use several speeding switches which operate automatically to accelerate the speed of the elevator motor but only one of such switches is herein indicated. The speed controlswitch SC is used to prevent the speed switch H from picking up until the elevator motor has attained a definite speed.

As has been described, the car of a high speed elevator, in a floor to floor run can be accelerated to only half speed and in making such a run the control switch SC is not picked up and consequently the speeding switch is not picked up. Whenhowever switch H is picked up it closes contacts 51 and 52, short circuiting the resist ance FR thereby increasing the voltage of the ourrent'from the generator and consequentlyincreasing the speed of the motor M.

When the switch H closes it also closes contacts 58 and 59 completing the circuit to a relay KU as follows:-From +L at 45 to 35 to contacts 58 and 59 to contacts 40 and 39 on switch U to 60 through magnet coil of KU to 61 to 63 on L. The flow of current through coil of KU causes it to pick up closing all its contacts.

When the relay switch KU is closed a circuit is also closed from switch TU through contacts 69 and 68 through 118 to contact b of the switching segment H'I'U.

When the relay KU is not closed, a circuit is completed from of TU on bottom contacts 67 and 66 to 116 to 117 on switching segment SRU and another circuit is completed through bottom contacts '71 and 70 to a of switching segment STU. i

It will thus be seen that when car is makin a floor to floor run, and car switch contacts 22 and 23 are closed, the direction switch U is closed but relay KU is not picked up and circuits are completed to slow speed timing segment STU and also to slow speed resistance segment SRU and even ii car switch completes circuit to contact 24 the speeding switch H does not pick up unless elevator has attained a speed tor a longer run and Operates the speed control switch SC to close the circuit to relay H.

The stopping switch'TU is set to open when the car is at a predetermined distance from the landing and the time adjustments are obtained by relays. Four relays are here shown TR1, TR2, TRS, and TR4,- a. larger or smaller number may be used if desired. These relays are so connected that if minimum time is wanted to 7 stop, TR1 only is picked up. If more time is wanted to make the stop TR2 and TR1 are picked up; if still more time is required TR3, TR2 and, TR1 are picked up and if the maximum time is required, all are picked up.

A flexible cable 116 is provided to the car with sufficient number of conductors to provide a circuit to each of the timing switches TR1-to TR4 and another flexible cable 167 to each of the resistance control switches RBI and RR3. These conductors may be combined in one cable if preferred, butare shown separately for convenience in showing the connections. The contact buttons adjoining the segments STU are bridged or grouped for connection to the conductor leading to the timing relay TR1 to TR4 that may be selected. Similarly contacts of HTU, STD and HTD will be grouped and connected to conductors to operate the desired timing relay. l V

In the same manner. the button contacts of SRU, HRU, SRD are grouped and connected with the conductors to operate the desired resistance control switches RRl to RR3.

For instance, assume that the load on the car is such as-to cause the bridging contact 109 of STU to assume the position shown and for this load the minimum stopping time is required, the button under the bridge 109 will be connected with the conductor 'lea/ding'to timing relay RRl at 134. This completes a circuit from +L at 113 through floor stop switch TU normally closed to 115 to contacts 71--70 of KU to 165 of STU through bridge contacts 115 through fiexible conductor to 84 through coil of TR1 to 88 to 92 to L at 93.

This causes TR1 to pick up closing its contacts 101-102 and complete a maintaining circuit for the direction switches as follows:--From +L at 94 through 105, 106, 107, 108 to contacts 101, 102 to 103m 104 where it branches to U or D, following circuit to U to contacts 34, 33 to 29 through coil to 30-to 31, 57 to L at 32. This causes direction switch U to remain closed after car switch has been centered until TR1 has opened.

Should brushes 109 engaging the segment contact a of STU span to a button connected with 83 of TR2 the circuit is completed through its coil to 87 to 91 and to L at 93. This causes TR2 to pick up closing contacts 99 and which completes circuit from +L' at 94, to 107, to 99 to 100 to 84 through coil to 88 to 92 to L at 93. This causes TR1 also to pick up. When stopping switch TU is opened the circuit to coil of TR2 is first broken,"I'R2 drops out, this opens contacts 99 and 100, thus breaking the circuit to TR1 which then drops out opening contacts 101 and Similarly when brushes 109 span from contact a to a button connected with 82 to TR3, first TR.3 picks up, then TR2 picks upand lastly TR1 picks up. When stopping switch TU is opened, TRB drops out, then TR2 drops out and finally TR1 drops out. The same procedure is followed if a button is connected with TR4. There is a small but definite time interval for each relay to deenergize and drop out and such time variation may be selected as is required after opening of stopping switch TU, to make a stop level with the landings.

Another set of relays MR1, RRl, RR2 and RRS are provided to regulate the strength of the demagnetizing current used on the generator for stopping. For purposes of illustration, a separate demagnetizing resistance winding DF is shown. S represents the generator series field, MSF represents the elevator motor shunt field and GSF referred to before, represents the generator shunt field. Contact segments SRU and HRU with their adjoining button contacts are provided on the switching box on car, the brushes 110 and 111 taking their position in accordance with the load on the car.

When relay TR1 picks up, it completes circuit from +L at 94 to 103 thence to to 121 through coil of relay MR1 to 122 to 123 on L. This causes MR1 to pick up closing contacts 124 and 125. Relay MR1 is constructed with a time lag so that it will not drop out immediately TR1 opens the contacts 101 and 102 but it will stay closed and keep contacts 124--125 closed until the elevator will have time to come to a stop.

The conductors from the button contacts of SRU and HRU are connected to terminals 142, 144, and 146 of the relays RRB, RR2 and R121 as may be selected to give the best stop of car at landing. If the brush 111 spans to a conductor connected with 146, the circuit is completed as follows:-From +L at 113 to contacts 41-42 to 114 and 115 of TU to contacts 67 and 66 of relay KU, when elevator is making a short fioor to floor run, to 116 to segment 0 of SRU. Across brushes 111 to button by flexible lead to 146 through coil of RBI to 147 to contacts 124 and 125 of MR1 to 122 and L at 123. This causes RBI to pick up, closing its contacts 134 and for a maintaining circuit as follows from +L at 126 to 127 to 129 to contacts 134 and 135 to 146 through coil to 147 to contacts 124125 to 122 and L at 123. This means that when stopping switch TU is opened and TR1 drops out, the relay RRl will not open until MR1 opens which it will not do until time is given for car to stop. RRl when it picks up closes contacts and 141 and these short circuit a. portion of the generator dem'agnetizing field resistance DFR at 150-151.

Similarly, if RR2 picks up,'it establishes its own maintaining circuit and short circuits DFR resistance from 149 to 151, and if RR3 picks up, it also establishes its own maintaining circuit and short circuits DFR resistance from 148 to 151.

MRl has also contacts 124-125 to close the circuit from +L at 126 through 127, 128, 129, 129 to contacts 124'125, to 169 where circuit divides to KU or KD, following to contacts 65-64 of KU to 60 forming a maintaining circuit to KU so that KU will remain closed after the car switch has been centered until MR1 has opened.

If elevator is making a longer run than one floor to floor relay KU picks up closing contacts 69 and 68 to d of segment HRU. The flexible conductors from HRU button contacts are connected with the terminal of the particular relay RRl, RR2 or RR3 as to give best stop.

It will be noted that the circuit of the demagnetizing field DF passes through the contacts 70 and 71 of up directionswitch U and of contacts 152 and 153 of down direction switch D so that both these switches must have opened before the demagnetizing field DF comes into action and the strength of the demagnetization may be varied by means of that resistanceDFR to control the stopping of the elevator,

The operations have been described fully for the up direction travel. For the down direction, they are quite similar and need not be detailed. The flexible leads from the button contacts STD for a single fioor run and from HTD for a longer run are connected to terminals 81, 82, 83 or 84 of relays TR4, TR3, TR2 or 'IRl as may be required to give best results for the time allowance in stopping in the down direction but the values will naturally not be the same as selected for the up direction stops as shown in values on chart Figure 1.

Similarly, the leads from button contacts SRD and HRD will be connected to terminals for RBI, RRZ or RR3 as required to give best values of demagnetizing generator field action. While only three of these relays are shown, it is understood that the number may be increased or decreased if advisable.

Experience has shown that while a certain value of demagnetizing field and a certain time for same to operate, will result in making an elevator stop each time level with the fioor with a fixed load and for one direction and length of travel, it has been found much more difficult to get the car to stop exactly at the same level with other loads on car and for both directions of travel, and different results are obtained in a single fioor run as compared with a longer run. In this invention, means are provided for readily selecting such values as to insure a stop level with fioor every time for all the above operating conditions.

With this invention, the strength of the demagnetizing field current may be kept stationary and the time varied; or the time may be kept stationary and the strength of the demagnetizing field current may be varied; or both the time and the strength of the demagnetizing field may be varied.

What I claim as my invention is:

1. An elevator control system, comprising an elevator car, a motor for operating said car, a generator supplying current to said motor and having field windings capable of neutralizing the residual magnetism of the generator, a resistance electrically connected with said windings, and weighing means controlled by the load on the elevator car for varying said resistance to regulate the values of the current produced by the generator to effect the stopping of the motor to stop the car at a desired point.

2. An elevator control system as claimed in claim 1 having a variable resistance controlled by a moveable element operatively engaging a plurality of fixed contacts, a Weighing device sup porting the car, and means connecting said moveable element with said weighing device to produce values of generator current which will stop claim 1 having a lever pivotally mounted on theelevator car and connected to the hoisting cables, means for varying the position of said lever in accordance with the car load, and a moveable contact device operatively connected with said lever andregulating said resistance to effect the demagnetizing of the residual magnetism of the generator in relation to the load on the car to effect the arresting of the motor and the resultant stopping of the car at a designated point.

4. An elevator control as claimed in claim 1 having a lever pivotally mounted on the elevator car and connected to the hoisting cables, means for varying the position of said lever in accordance with the car load, a moveable contact device operatively connected with said lever and having a plurality of sets of contact members thereon, groups of fixed contacts co-operating with said sets of contact members on said moveable device, a resistance connected with the field windings, and means interposed between said fixed contacts and said resistance for effecting the control of the fiow of current to demagnetize the residual'magnetism in the generator.

5. An elevator control as claimed in claim 1 having a lever pivotally mounted on the elevator car and connected to the hoisting cables, means for varying the position of said lever in accordance with the car load, a moveable contact device operatively connected with said lever and having a plurality of sets of contact members thereon, groups of fixed contacts co-operating with said sets of contact members on saidmoveable device, certain of said groups of contacts being used for up travel for slow speed runs, others for up travel forhigh speed runs, certain other of said groups of contacts being used for down travel for slow speed runs, others for down travel high speed runs.

6. An elevator control system comprising, an elevator car, a motor operating said car, a generator supplying current to said motor and having field windings adapted to receive a demagnetizing current,--said field windings being used to demagnetizethe residual magnetism of the generator, and weighing means controlled by the load on the car for varying the period of application of the demagnetizing current to said generator field.

7. An elevator control system as claimed in claim 6, having a lever pivotally mounted on theelevator car and connected with the hoisting cables, means for varying the position of said lever in accordance with the car load, a moveable contact device operatively connected with said lever and having a plurality of sets of contact members thereon, groups of fixed contacts co-operating with said contact members on said moveable device, certain of these said contacts being used for up travel slow speed runs others for up travel high speed runs, certain of said contacts being used for down travel slow speed runs and others for down travel high speed runs for effecting the control of the period of application of the demagnetizing current to the generator windings.

8. An elevator control system comprising an elevator car, a motor for operating said car, a generator supplying current to said motor and having field windings through which a demagnetizing current is adapted to be passed, a resistance electrically connected with the field windings of said generator, said field windings being used to demagnetize theresidual magnetism of the generator, and weighing means controlled by the load on the elevator car for varying said resistance toregulate the value of the current and for controlling the period of application of said current to the field windings to effect the demagnet'ization of the generator to effect the stopping of the motor to stop the car at a desired point.

9. An elevator control having a weighing device mounted on the elevator car and connected to the hoisting cables, a motor for operating said cables, a generator having windings through which a demagnetizing current is adapted to be passed to offset the residual magnetism thereof, said generator supplying current to said motor, means for varying the position of said weighing device in accordance with the car load, a moveable contact device operatively connected with said weighing device and having a plurality of sets of contact members thereon, groups of fixed contacts co-operating with said contact members on said moveable device, means connected with certain of said fixed contacts for effecting the control of the current to demagnetize the residual magnetism of the generator, and means connected with other of said fixed contacts for effecting control of the period of application of such demagnetizing current to effect the stopping of the car at a desired point.

10. An elevator control as claimed in claim 8 having a moveable contact device operatively connected with said weighing means and having a plurality of sets of contact members thereon, a group or" fixed contacts co-operating with a set of contact members on said moveable device and effecting the control of the period of application of a demagnetizing current to the generator in the up travel of the elevator, a group of fixed contacts arranged to co-operate with other of the contact members on said moveable contact device and effecting the control of the period of application of a demagnetizing current to the generator in the down travel of the elevator, a group of fixed contacts arranged to co-operate with other of the contact members on said moveable contact device and effecting the control of the flow of a demagnetizing current to the generator in the up travel of the elevator, and a group of fixed contacts arranged to co-operate with others of the moveable contacts controlling the flow of demagnetizing current to the generator on the down travel.

11. An elevator control as claimed in claim 9 having a plurality of groups of fixed contacts ccoperating with the contacts on said moveable device, certain of said groups of contacts controlling the selection of the flow of a demagnetizing current to pass through the generator windings and others of said groups of contacts controlling the period of application of flow of the demagnetizing current to produce a currentvalue to cause the elevator to come to a stop at a predetermined point.

12. An elevator control system, comprising a motor for operating the elevator, a generator for supplying current to the motor and having a field, a demagnetizing field, a demagnetizing field resistance, a plurality of relays connected with said demagnetizing field resistance, contacts arranged in groups selectively connected with said resistance relays, an operable member having contacts adapted to progressively engage the contacts connected with said relays and complete electric circuits thereto, means for supporting the car operably connected to said moveable contact carrying device and moveable in accordance with the load on the car and adapted to operate said resistance relays and effecting demagnetization of the generator to control the movement of the motor to stop the car.

13. An elevator control system, comprising a motor for operating the elevator, a generator for supplying current to the motor and having a field, a demagnetizing field, a plurality of relays for controlling the period of application of electric current to said demagnetizing field, fixed contacts arranged in groups selectively connected with said relays, an operable member having contacts adapted to progressively engage the contacts connected with said relays and complete electric circuits'thereto, means for supporting the car operably connected to said moveable contact carrying device and moveable in accordance with the load on the car and adapted to operate said relays effecting the demagnetization of the gen rator to control the movement of the mctor to stop the car.

14. An elevator control device, comprising the combination with the car and its supporting cables, of a lever pivotally mounted in the car and connected to said cables, means operative in accordance with the load in the car for controlling the movement of said lever, a rotatable device operatively connected to said lever and having a plurality of arms, a plurality of contacts carried by each of said arms, a plurality of fixed contacts arranged to co-operate with the contacts on said arms in the rotary movement of said member, a plurality of timing relays connected with certain of the fixed contacts engaged by the contacts of the rotary device, a plurality of relays electrically connected with the fixed contacts to be engaged by other contacts of said rotary device, a generator having a demagnetizing field, a resistance arranged in the demagnetizing field circuit of said generator and connected with the latter relays, and a motor controlled by the current produced by said generator.

HARRY C. TU RNBULL. 

